Question 1

Which cloud type is associated with thunderstorms, waterspouts, and very heavy localised rain?

Accepted Answer

Cumulonimbus (Cb), a towering cloud with strong vertical development.. CUMULONIMBUS (Cb): the thundercloud, vertically developed to 40,000ft or more, anvil top (cirrus-like), associated with: heavy rain or hail; lightning and thunder; waterspouts (marine tornados); violent squalls with sudden wind shifts; extreme turbulence. Preceded by rapidly building cumulus towers. A Cb approaching from the SW in UK waters is a serious hazard requiring immediate sail reduction and crew preparation.

Question 2

You observe high, thin, wispy cloud at altitude with a mare's tail appearance. What cloud type is this and what does it indicate?

Accepted Answer

Cirrus, often the first sign of an approaching warm front, appearing 12 to 24 hours ahead.. CIRRUS (Ci): high-altitude ice crystal cloud (above 20,000ft), thin, wispy, feathery or mare's tail appearance. Often the first visible sign of an approaching warm front, appearing 12-24 hours before the front arrives. Sequence: Ci → Cirrostratus (halo) → Altostratus → Nimbostratus (rain). Cirrus alone does not guarantee a front, it can appear in isolated patches in settled anticyclonic weather. But persistent, thickening cirrus spreading across the sky = front approaching.

Question 3

How do you recognise an approaching cumulonimbus (Cb) cloud and what action should you take?

Accepted Answer

Rapid vertical growth, anvil, dark base, possible lightning: reef immediately, secure gear, don lifejackets, steer clear of its track; avoid sheltering beneath.. CB RECOGNITION AND ACTION: APPEARANCE: rapidly growing cumulus towers, dark threatening base, anvil top (cirrus spreading at top, storm mature), lightning flashes. APPROACH: wind often dies before Cb arrives (deceptive), then violent squall hits, can go from calm to F7-8 in minutes. ACTION: REEF IMMEDIATELY when Cb is spotted approaching. Secure all loose gear. Crew in harnesses/lifejackets. Bear away from its track, they travel with the wind. NEVER shelter under or near a Cb, lightning, waterspouts, violent downdrafts.

Cloud Types, questions and explanations

Which cloud type is associated with thunderstorms, waterspouts, and very heavy localised rain?

You observe high, thin, wispy cloud at altitude with a mare's tail appearance. What cloud type is this and what does it indicate?

How do you recognise an approaching cumulonimbus (Cb) cloud and what action should you take?

Practise this properly

Cloud Types, questions and explanations

Questions

Which cloud type is associated with thunderstorms, waterspouts, and very heavy localised rain?

You observe high, thin, wispy cloud at altitude with a mare's tail appearance. What cloud type is this and what does it indicate?

How do you recognise an approaching cumulonimbus (Cb) cloud and what action should you take?

Practise this properly